jetta stereo replaced

I replaced the head unit in my '00 vw jetta about 3 months ago, and last week the check engine light somes on. so i hook up the code reader that worked on my car and now it says no connection. i have tried everything i can to figure out what is wrong with my OBD II but all the wires have power apllied. the old stereo was completely burned up and would not work even with all the fuses replaced. so now i need to figure out whats wrong with my car and am stuck. the dealership got the no connection as well.........

can anyone help? :banghead:

Some aftermarket radios will interfere with the OBD connection. In fact, some dealers will not even attempt to read your codes if you have an aftermarket radio. Find a used stock radio.